1. Field of the Invention
The present invention relates to a seat back board, a trim cover and a vehicle seat.
2. Description of the Related Art
A seat in which a back surface of a seat back of a front seat is formed in a recess shape to enlarge a leg space of a rear-seat occupant is known as a seat to be mounted in a vehicle such as an automobile. Such a kind of seat includes a relatively rigid seat back board made of a resin material. Typically, the seat back board is fixed to a wire, a bracket, or the like which is attached in a seat back frame through a hook, a clip, or the like.
In a seat back board described in JP-A-2013-47076, a carpet is joined with the lower portion of the seat back board, and the lower end portion of a seat back and the bottom surface of a seat cushion are covered with the carpet to improve the appearance of the seat.
In a seat back for automobile described in JP-A-2009-291599, the back surface of the seat back is covered with molded nonwoven fabric. The molded nonwoven fabric is impregnated with a synthetic resin to be molded in a concavo-convex shape and is soft to be sewable. The molded nonwoven fabric is sewn with a front surface skin which covers the front surface of the seat back or is sewn with a slide fastener which is coupled with the front surface skin in a detachable manner.
Further, a bent portion which covers the lower end portion of the seat back and the bottom surface of the seat cushion is provided to be integrated with the lower portion of the molded nonwoven fabric.
Typically, the relatively rigid seat back board is fixed to the wire, the bracket, or the like which is attached in the seat back frame. However, the wire, the bracket, or the like is needed for the seat back frame, so that the number of components of the seat may be increased.
As the seat back board described in JP-A-2013-47076, in order to cover the lower end portion of the seat back and the bottom surface of the seat cushion, the carpet which is joined with the lower portion of the seat back board is needed additionally. Thus, the number of components may be increased, the number of manhours may be increased due to the joining of the seat back board and the carpet, and the appearance may deteriorate due to the joining of the seat back board and the carpet.
Also, in the seat back for automobile described in JP-A-2009-291599, for example, the relatively soft molded nonwoven fabric which covers the back surface of the seat back is sewn with the front surface skin covering the front surface of the seat back to be fixed in the seat back. In addition, the molded nonwoven fabric integrally includes the bent portion which covers the lower end portion of the seat back and the bottom surface of the seat cushion.
Incidentally, as for the shape of the back surface of the seat back, a requirement such as a curvature radius of a surface and a height of a protrusion is regulated by the law such as Safety Standards for Road Transport Vehicles (Appendix 30: technical standards of seat and seat installation device) and European Commission Regulations (UN-R17-08). Under such a law, a relatively soft material such as molded nonwoven fabric, specifically, a material having the Shore hardness of 50 or lower is not admitted as a component which forms the back surface of the seat back, and the back surface of the seat back is required to satisfy the requirement in a state where the molded nonwoven fabric is removed. In this case, a rounding process of an edge of the seat back frame, a squeezing process of the protrusion, and the like are needed so that the number of manhours may be increased, or a cover which covers and hides the edge, the protrusion, or the like is needed so that the number of components may be increased.